The semiconductor industry has recently experienced technological advances that have permitted dramatic increases in circuit density and complexity, and equally dramatic decreases in power consumption and package sizes. Present semiconductor technology now permits single-chip microprocessors with many millions of transistors operating at speeds of hundreds of millions of instructions per second to be packaged in relatively small, air-cooled semiconductor device packages. A by-product of such high-density and high functionality has been an increase in the number and complexity of the manufacturing processes, as well as an increase in the difficulty of maintaining satisfactory levels of quality control and of providing a cost-effective product using such processes.
As the manufacturing processes for semiconductor devices increase in difficulty, methods for analyzing and repairing the devices become increasingly important. Not only is it important to ensure that individual chips are functional, it is also important to ensure that batches of chips perform consistently. In addition, the ability to detect a defective manufacturing process early is helpful for reducing the number of defective devices manufactured.
Various attributes of individual circuit elements and combinations in a semiconductor device may be tested by exciting selected areas of circuitry in the device. Testing these attributes provides an opportunity for determining such things as the integrity of the semiconductor device or, for defective devices, determining a reason for the defect. Ensuring the integrity and determining defect sources in such devices is important for maintaining proper device function, reliability, and longevity, and for improving the manufacturing process. Unfortunately, access to device circuitry for performing such analysis is difficult, and available testing methods are often impractical or otherwise inefficient. Furthermore, structure within the device is often damaged during analysis, and needs to be repaired in order to function.